Studies are being carried out on the following aspects of the synthesis and assembly of the microtubules of Chlamydomonas flagella: (a) Flagellar proteins are being analysed in the cytoplasm of Chlamydomonas at different stages of flagellar regeneration to determine their sequence of entry into the assembled flagella and to determine if certain flagellar proteins must undergo post-translational processing in the cytoplasm before they are assembled into the flagella; (b) the appearance of flagellar proteins in the cytoplasm of Chlamydomonas is being analysed under conditions in which the flagella are amputated but are not permitted to elongate (by use of colchicine), or under conditions where the flagella are experimentally resorbed into the cytoplasm; (c) temperature-sensitive (cold and warm) mutants for Chlamydomonas flagellar development are being isolated and the flagellar proteins are being analysed in the cytoplasm and flagella at permissive and non-permissive temperatures; matings between mutant and wild-type cells are being done to determine if abnormalities in flagellar structure, function and development can be analyzed by in vivo complementation; (d) the assembly of flagellar microtubules in vitro is being studied to determine the requirements for axonemal microtubule assembly and especially the (possible) role of microtubule-associated proteins in microtubule assembly; (e) cell free proteins synthesis on polysomes isolated from Chlamydomonas is being used to study the in vitro synthesis of flagellar tubulin and other flagellar proteins at different stages of flagellar regeneration and under conditions where the flagella are experimentally induced to resorb. BIBLIOGRAPHIC REFERENCES: Dentler, W. and J. Rosenbaum. 1977. Flagellar elongation and shortening in Chlamydomonas. III. Structures attached to the tips of the flagellar microtubules and their relationship to the directionality of flagellar microtubule assembly. J. Cell Biol. in press. Sloboda, R., Dentler, W. and J. Rosenbaum. 1976. Microtubule-associated proteins and the stimulation of tubulin assembly in vitro. Biochemistry, 15, 4497-4505.